Fixed corners of Simulation Program with Integrated Circuit Emphasis (SPICE) models are widely used in semiconductor chip design (e.g., VLSI circuit designs) for best and worst case performance estimation. Fixed corner parameters, however, are typically related to either digital or analog performance since it is difficult to capture both analog and digital variations in the same corner with current model equations. As such, designers are forced to separately validate their circuits with a digital corner for digital block designs and an analog corner for analog block designs. That is, traditional fixed corner configurations will not allow designers to analyze a circuit using different corners for digital and analog blocks of the circuit at the same time. Consequently, designers are burdened with higher costs with respect to time and resources since they must separately analyze the circuit using different corners and then verify the results of each analysis.
A need therefore exists for sub-circuit models with corner instances.